
Once you have your spouse's details added, LTP allows you to input additional spouse data for Salary, Retirement Benefits, Investments and others. Click on the ? icon in the About You dialog in image 1. LTPs's help section is generally pretty good.
A note re: Investments. To assign an investment, retirement, et al account owner (you or your spouse): In the Planning Assumptions window, go to Investments and highlight an Investment Account, click on Details button, then assign ownership.